1. Field of the Inventive Concept
Apparatuses and methods consistent with the present inventive concept relate to a vibration proof zoom lens and a photographing apparatus having the same.
2. Description of the Related Art
There have been proposed various zoom lenses with a device (vibration-proofing apparatus) compensating for image shaking caused by vibrations fortuitously transmitted to a photographing system. For instance, there is known a zoom lens (vibration proof zoom lens), in which to compensate for the image shaking caused by the vibrations, moves a portion of lens groups forming the zoom lens in a vertical direction to an optical axis.
Examples of such a zoom lens are disclosed in, for example, Japanese Patent Laid-open Nos. 2006-106191 and 2009-284763. The disclosed zoom lenses (vibration proof zoom lenses), which have a vibration proof function, are composed of a first lens group with a positive refractive power, a second lens group with a negative refractive power, a third lens group with a positive refractive power, and a fourth lens group with a positive refractive power, which are arranged in order from an object side, respectively. The third lens group consists of a front group with a positive refractive power and a rear group with a negative refractive power, and the rear group is moved in the vertical direction to the optical axis to compensate for the image shaking.
In the zoom lenses disclosed in Japanese patent laid-open Nos. 2006-106191 and 2009-284763, a focusing operation from a far distance to a close distance is performed by moving the second lens group toward the object side.
On the other hand, there are known various methods of focusing the zoom lens to the close distance. For instance, there is known an optical system in which a most front lens can be restrained in diameter and which as a zoom lens desirable for high variable-magnifying or zooming, has a first lens group with a positive refractive power, a second lens group with a negative refractive power and a third lens group with a positive lens refractive power arranged in order from the object side (see, for example, Japanese Patent Laid-open Nos. H10-133109 and H10-133111). In the optical system, the focusing is performed at the third lens group.
In the conventional vibration proof zoom lenses as described above, however, problems have been discovered, as follows:
The zoom lenses disclosed in Japanese patent laid-open Nos. 2006-106191 and 2009-284763 perform the focusing by moving the second lens group. In the zoom lenses, however, since the second lens group with the negative refractive power preceding the first lens group with the positive refractive power generally contributes to a major variable magnification among the entire optical system, it has a relatively large number of lenses, and is large even in mass. For instance, the second lens group disclosed in the Japanese patent laid-open Nos. 2006-106191 and 2009-284763 is composed of four lenses, which include a negative meniscus lens having a convex surface toward the object side, a bi-concave lens, a bi-convex lens and a negative meniscus lens having a concave surface toward the object side.
On this account, there are problems in that it is difficult to control the second lens group to move forward and rearward in very small amounts and is not adapted to, particularly, a so-called contrast detection type auto focus by a blur detection of an image pickup device.
Also, the zoom lenses disclosed in Japanese Patent Laid-open Nos. H10-133109 and H10-133111 perform the focusing at the third lens group with a positive refractive power. In the zoom lenses, however, since the third lens group is composed of three cemented lens, each of in which a positive lens, a positive lens and a negative lens are cemented with one another, there are problems in that this third lens group also has a relatively large number of lenses and is not adapted to, particularly, the so-called contrast detection type auto focus.
On this account, there is a need for a vibration proof zoom lens, which establishes a sufficient close distance while having a high variable-magnification and a good optical performance, and which is adapted to, particularly, the contrast detection type auto-focus by the blur detection of the image pickup device.